The continued demand for higher personal computer processing speed calls for increasingly smaller features on wafers. The demand for smaller features places greater demands on optical lithography systems and the associated metrology of wafers. With features becoming exponentially smaller, geometrical uniformity throughout a wafer is becoming increasingly useful.
Sensitivity analysis is a technique used to determine how different values of an independent variable will impact a particular dependent variable (e.g. wafer film thickness) under a given set of conditions (chamber parameters). Sensitivity analysis on wafers is beneficial to determine how different wafer recipe parameters affect wafer film thickness, for example.
Typically, sensitivity analysis outputs are viewed and analyzed in terms of a single, average sensitivity across an entire wafer. More sophisticated methods provide radial sensitivity values across a wafer, where sensitivity values are determined for several radial intercepts across the wafer.